 /*******************************************************************************
  * Copyright (c) 2000, 2005 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.ui.texteditor;


 import java.util.ResourceBundle ;

 import org.eclipse.swt.custom.BusyIndicator;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.Shell;

 import org.eclipse.jface.text.ITextOperationTarget;
 import org.eclipse.jface.text.ITextOperationTargetExtension;
 import org.eclipse.jface.text.source.ISourceViewer;

 import org.eclipse.ui.IWorkbenchPartSite;


 /**
  * A content assist action which gets its target from its text editor.
  * <p>
  * The action is initially associated with a text editor via the constructor,
  * but can subsequently be changed using <code>setEditor</code>.</p>
  * <p>
  * If this class is used as is, it works by asking the text editor for its text operation target
  * (using <code>getAdapter(ITextOperationTarget.class)</code> and runs the content assist
  * operation on this target.
  * </p>
  * @since 2.0
  */
 public final class ContentAssistAction extends TextEditorAction {

     /** The text operation target */
     private ITextOperationTarget fOperationTarget;

     /**
      * Creates and initializes the action for the given text editor.
      * The action configures its visual representation from the given resource
      * bundle. The action works by asking the text editor at the time for its
      * text operation target adapter (using
      * <code>getAdapter(ITextOperationTarget.class)</code>. The action runs the
      * content assist operation on this target.
      *
      * @param bundle the resource bundle
      * @param prefix a prefix to be prepended to the various resource keys
      * (described in <code>ResourceAction</code> constructor), or
      * <code>null</code> if none
      * @param editor the text editor
      * @see ResourceAction#ResourceAction(ResourceBundle, String)
      */
     public ContentAssistAction(ResourceBundle bundle, String prefix, ITextEditor editor) {
         super(bundle, prefix, editor);
     }

     /**
      * Runs the content assist operation on the editor's text operation target.
      */
     public void run() {
         if (fOperationTarget != null) {

             ITextEditor editor= getTextEditor();
             if (editor != null && validateEditorInputState()) {

                 Display display= null;

                 IWorkbenchPartSite site= editor.getSite();
                 Shell shell= site.getShell();
                 if (shell != null && !shell.isDisposed())
                     display= shell.getDisplay();

                 BusyIndicator.showWhile(display, new Runnable () {
                     public void run() {
                         fOperationTarget.doOperation(ISourceViewer.CONTENTASSIST_PROPOSALS);
                     }
                 });
             }
         }
     }

     /**
      * The <code>ContentAssistAction</code> implementation of this
      * <code>IUpdate</code> method discovers the operation through the current
      * editor's <code>ITextOperationTarget</code> adapter, and sets the
      * enabled state accordingly.
      */
     public void update() {

         ITextEditor editor= getTextEditor();

         if (fOperationTarget == null && editor!= null)
             fOperationTarget= (ITextOperationTarget) editor.getAdapter(ITextOperationTarget.class);

         if (fOperationTarget == null) {
             setEnabled(false);
             return;
         }

         if (fOperationTarget instanceof ITextOperationTargetExtension) {
             ITextOperationTargetExtension targetExtension= (ITextOperationTargetExtension) fOperationTarget;
             targetExtension.enableOperation(ISourceViewer.CONTENTASSIST_PROPOSALS, canModifyEditor());
         }

         setEnabled(fOperationTarget.canDoOperation(ISourceViewer.CONTENTASSIST_PROPOSALS));
     }

     /**
      * @see TextEditorAction#setEditor(ITextEditor)
      */
     public void setEditor(ITextEditor editor) {
         super.setEditor(editor);
         fOperationTarget= null;
     }
 }

